energy p2 Flashcards
how does food give you energy and what do you need to have it.
energy and machines
Different food stores different amount of energy. Food labels tell you how much energy is stored in the food. Fuels such as coal and oil also store energy. Oxygen is needed to burn fuels. Energy released in the burning of fuels helps to power homes. If you take in more energy than you need your body stores it as fat to use in the future.
what are some forms of energy
Energy stored in food and fuels are known as chemical store of energy. Other forms of energy stores are kinetic (movement), thermal (heat), elastic and gravitational potential (stationary). After you use your phone, there is less energy in the chemical store and more energy in the thermal store of the surroundings. Forces, not energy, explain why things move.
what does a higher temprature mean
The higher the temperature the more the particles move in the form of vibration. The cold Arctic ocean contains more thermal energy than a hot cup of tea. Heating a solid makes the particles vibrate more. The energy that you need to increase the temperature of a material depends on the mass of material, what the material is made of and the temperature rise.
why is a metal a good conductor
A metal is a good conductor of energy because metals contain a free electrons that carry the energy through the metal. In conduction particles transfer their energy by colliding with other particles when they vibrate. Energy does not flow very well through insulators e.g. air, wood. This is because there are no free electrons to carry the energy.
what are some fact about radiation
Radiation is a transfer of energy that does not need particles. Energy from the sun is radiated through space to Earth by infrared radiation. The type of radiation emitted depends on their temperature. Space is a vacuum because there are no particles in space. Dark clothes absorb more infrared radiation. Light coloured and shiny surfaces reflect infrared radiation.
what are fuels
Coal, oil, and gas were formed millions of years ago from the remains of algae and plant material. They are non-renewable, so once used up, they are gone forever. In a power station a fuel is burnt to heat water to produce steam, which turns a turbine, and then spins a generator to produce electricity. Renewable energy never runs out e.g. wind, sunlight, tidal, waves, solar and biomass.
what is power
Power is how much energy is transferred in a second or rate of transfer of energy. Power is measured in Watts (W). Electricity bill is calculated in kilowatt hour because of the huge amount of electrical energy transferred by appliances. Power is energy divided by time. To reduce your energy bills you could use fewer appliances, or appliances that require less power to run.
what is work
Energy can be transferred by doing work. For instance you do work by lifting a book against gravity. Work done (J) = force (N) × distance (m). A simple machine makes it easier to lift things, move things, or turn things. It reduces the force that you need do a job, or increases the distance that something moves when you apply a force. The gear system on a bike is a simple machine.
